The present invention relates generally to satellite maneuvering methods, and more particularly, to a method of perigee velocity augmentation that provides for maneuvering a relatively heavy satellite and raising the apogee point of an elliptical transfer orbit to geosynchronous altitude.
Because of the ever-increasing mass of geostationary satellites, these satellites are delivered into subsynchronous transfer orbits due to limited launch vehicle capability. That is, the initial orbits of the satellite has a low perigee altitude (200-300 kilometers) and an apogee radius that is below the synchronous radius value of 42,164 kilometers. In order to raise the apogee radius to its synchronous value, perigee velocity augmentation is employed. Perigee velocity augmentation involves firing satellite thrusters in the vicinity of orbit perigee to raise the apogee of the orbit to the synchronous radius. After this is achieved, normal orbit raising operations are undertaken.
One previous approach to perigee velocity augmentation is to orient the satellite into the correct attitude such that its thrust vector is oriented directly opposite to the direction of motion of the satellite exactly at the satellite's perigee point. The satellite maintains this inertial attitude for the entirety of the maneuver. This approach to perigee velocity augmentation is adequate but is not very efficient.
Several approaches to perigee velocity augmentation are described in a paper entitled "Perigee Velocity Augmentation for Synchronous Mission", by E. L. Williams, published in the proceedings of the AIAA 20th Aerospace Sciences Meeting, Jan. 11-14, 1982. This paper discusses perigee velocity augmentation in general and describes three augmentation techniques known as "perigee/perigee", "perigee/apogee" and the "fire in the hole" techniques. Each technique is described in detail, and analysis is provided, as it relates to a particular launch vehicle and satellite configuration. The content of this paper is incorporated herein in its entirety by reference.
Therefore, it is an objective of the present invention to provide for a method of perigee velocity augmentation that is relatively efficient, and wherein this increased efficiency allows a satellite of greater mass to be delivered into geosynchronous orbit.